NOW THAT the Republican nominating process is basically over, bystander Americans can ask: What was that all about? Last week, President Obama characterized the budget positions of Republicans as social Darwinism - survival of the fittest, and to hell with the rest. In one sense, the reference to the father of evolutionary theory was exactly wrong: To my eyes, the positions of GOP presidential hopefuls on broadly human questions - “values’’ - look like a willful replay of monkey-trial cluelessness. Yet this very campaign speaks to how rapidly our society is evolving, and it isn’t only the Republicans who are grasping at how to respond.

In our democracy, politics is about much more than elections. Through public discussion of large questions, we can reckon with the deep uneasiness that comes with unprecedented change. Indeed, the Republican candidates have done the whole society a service by forcing a confrontation with just how profound the ongoing transformation of our culture is. Even as they make outlandish comments about everything from self-deporting immigrants to a return to the gold standard, the level of apprehension that they have brought to the surface belongs to everyone.

The most pronounced signifier that emerged from the GOP free-for-all is birth control, and its contentiousness points right back to a lingering unease with, well, Charles Darwin. Abortion and gay marriage have long been hot-button issues, but when birth control tops the fight card, something odd is happening. Rick Santorum can wield contraception as a cudgel, with his competitors feeling obliged to grab it with him, because far-right conservatives (who mostly practice birth control themselves) fixate on birth control as code for something else.

Most obviously, the something else is the place of women, whose move to full social equality was jump-started by the 20th-century invention of reliable contraception. People who are unsettled by this shift and its consequences, male and female alike, might well settle on birth control as the thing to blame. Furthermore, birth control enables the universal separation of sex for reproduction from sex for pleasure and intimacy. That separation would be enough to prompt repudiation by puritans, but it also opens to our era’s acceptance of homosexuality - sexual intimacy with no reproductive purpose.

But birth control’s most radical effect lies in the deeper challenge it poses to the meaning of “natural,’’ hence the indictment of it by the Catholic hierarchy as “unnatural.’’ That brings us back to Darwin. Before him, “nature’’ was taken to be apart from “us’’; the human species was thought to be unique - the pinnacle and purpose of creation. But Darwin locates the human species firmly within nature, so much so that, yes, the monkey could be seen as a cousin. The idea of a static “natural law’’ to which humans must eternally conform gives way to a dynamic ethic which applies fundamental moral principles to ever-shifting conditions. And with human nature endlessly changing, behaviors and moral norms must be constantly re-evaluated and re-created. Our taking charge of reproduction - even to the point of changing it altogether through new technologies like cloning and genetic engineering - epitomizes the post-Darwin project.

This is a move into unsettling new territory, and not only for conservatives. Through their embrace of the environmental movement, liberals struggle to reconcile the protection of the natural world with humans’ specific needs. The task is to find ways to bring these hidden pressures into the light, to think about them publicly, and to advance solutions together to the problems posed by the massive cultural mutations that are underway.

Politics is one of the important ways we do this. And because so many of the forces at work beneath the surface of culture are themselves irrational and frightening, there should be no surprise that our politics can be irrational and frightening, too. In this season, we owe a debt to the frantic Republican contest for raising questions that seemed to be settled, but weren’t - for reminding Americans that, amid all that separates us, we are alike in being challenged by new meanings of the human condition.